Mmm. "Nothing" to do? Whenever I get some downtime at school or work, I'm pretty much always going to have some other work I can be doing... be that schoolwork or just roleplay-related stuff. In fact, assuming I'm in an awake and focused state, I'll actually get somewhat annoyed/anxious if I have downtime and no work I can be doing, so I pretty much always have that sort of thing in mind whenever I'm packing up my backpack or whatever. If I somehow don't have anything to work on, or I'm in a situation where it wouldn't be easy to do (like, standing in a long line), then I'll probably whip out my phone and check my email, maybe poke around Iwaku a bit, or check Pokemon Go -- although I pretty much always have that on throughout most of the day, unless I'm going to be sitting in one place for a while and/or I'm really trying to focus on something.
Meanwhile, if my "boredom" comes more from the fact that I'm spacing out and therefore getting work done in my downtime feels kind of pointless because I would keep getting distracted and zoning out again just in the steps it takes to get everything out of my backback and start working on it? Well then I don't really need to find anything to do, because, whether I like it or not, my mind will drift off and I'll spend the next half-hour thinking about that Sonic cameo in Wreck-It Ralph and wondering whether or not that was supposed to be a reference to those awkward PSA's that the Sonic cartoon did way-back-when or if I'm just overthinking it and perhaps giving them too much credit. ...Although, if I'm waiting around bored for an exceptionally long stretch of time, then I'll also probably start poking around at my phone or something. Just depends on what kind of mood I am and what level of spacey I'm at, I guess.